2.0 Analysis 2.1 Securing Arrangement Because no turn-buckles or other tightening or wedging devices were used and because there was no arrangement to secure the door where it was in contact with the deck, it would not have been possible to render the door completely immobile. The scratch marks on the deck could be considered as being consistent with movement of the door when in the stowed position. The rolling of the CAPE BRIER as she operated in the seaway would subject the securing arrangement to repeated snatch/shock loads. The intended stowage recesses in the ship-side bulwarks had not been modified to take the larger doors, but proper immobilization of the doors could have been achieved without major structural alterations. The addition of minimal fittings such as eye-pads and angles to the deck and bulwarks would have permitted a rigid stow of the doors in the alternate location. 2.2 Failure of the Securing Arrangement Because of the many variable factors involved, it was not possible to determine the load to which the securing arrangement would have been subjected. The manufacturer's minimum breaking load for the coupling links, which the tested links exceeded, was in the order of 30 times the weight of the door. No parts of the coupling link which connected the securing arrangement to the door were recovered, suggesting that the alloy pin failed in shear or that the pin worked its way out. The TSB Engineering Laboratory report suggests that the most probable failure scenario was that the load pin could have slipped out of the missing coupling link if there was wastage of the stud assembly due to corrosion. 3.0 Conclusions 3.1 Findings Introduction of larger mid-water trawl doors required that alternate stowage be found on the vessel for these doors. No provision was made to facilitate the securing of the doors at the selected alternate stowage sites. The securing arrangements made did not incorporate any tightening or chocking devices. With the doors not rigidly stowed, the securing chains were subject to cyclical shock loading when the vessel was working in a seaway. The integrity of the securing arrangements relied on the crew monitoring the condition of the components. One of the coupling links incorporated in the securing arrangement for the door that came loose could not be located after the accident. The normal operation of the vessel required that crew members work in the vicinity of the stowed doors. Prompt first-aid efforts by crew members could not resuscitate the victim. 3.2 Causes The trawl door on the CAPE BRIER came loose because it had not been adequately secured against the vessel's movement in the sea conditions in which she was operating. 4.0 Safety Action 4.1 Action Taken 4.1.1 Modification by Owners Following the accident, the vessel owners fitted storage pockets on two similar class vessels in order to properly secure large mid-water trawl doors. Since there are only two pairs of large mid-water doors in the fleet, they will be permanently assigned to the modified vessels. A total of four vessels of the same class were modified and fitted with storage pockets for the proper securing of ground trawl doors. 4.1.2 Stowage of Enlarged Trawl Doors The TSB has no records of similar occurrences. However, given the unsafe condition which could exist on other vessels utilizing trawl doors larger than those for which the securing pockets are designed, the TSB apprised the Canadian Coast Guard of the circumstances of this occurrence.